glibc/sysdeps/unix/sysv/tcsendbrk.c

/* Copyright (C) 1992, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <stddef.h>
#include <signal.h>
#include <termios.h>
#include <unistd.h>
#include <sysv_termio.h>
#include <sys/ioctl.h>

/* Send zero bits on FD.  */
int
tcsendbreak (fd, duration)
     int fd;
     int duration;
{
  /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
     and an implementation-defined period if DURATION is nonzero.
     We define a positive DURATION to be number of milliseconds to break.  */
  if (duration <= 0)
    return __ioctl (fd, _TCSBRK, 0);

  /* ioctl can't send a break of any other duration for us.
     This could be changed to use trickery (e.g. lower speed and
     send a '\0') to send the break, but for now just return an error.  */
  __set_errno (EINVAL);
  return -1;
}